Tunisia's Islamist Ennahda party has won elections with 41.5 per cent of votes cast, nine months after the toppling of longtime-ruler Zine el Abidine Ben Ali.

The party obtained 90 seats in a new 217-member assembly that will rewrite the constitution, appoint a president and form a caretaker government, elections chief Kamel Jendoubi announced in Tunis on Thursday.

The leftist Congress for the Republic (CPR) was in second place with 13.8 per cent, representing 30 seats, and Ettakatol third with 9.7 per cent or 21 seats, he said.

Meanwhile, protests linked to the party placing fourth in Sunday's voting erupted in and around Sidi Bouzid, the town where the uprising that drove Ben Ali from power began.

Protesters there were angry that election officials had cancelled seats won by Areedha Chaabiya, or the Popular List, a party led by businessman Hachmi Hamdi, over alleged campaign finance violations.

More than 2,000 young people marched on the Sidi Bouzid headquarters of Ennahda, burned tyres and pelted security forces with stones.

Protests spread to nearby Menzel Bouzayane where more than 1,000 people demonstrated, union official Mohamed Fadhel said. In Meknassy, 50km from Sidi Bouzid, demonstrators set fire to Ennahda's party office, Fadhel said.

Forming an assembly

After Ennahda was officially declared the winner, its leader Rachid Ghannouchi said: "We will continue this revolution to realise its aims of a Tunisia that is free, independent, developing and prosperous in which the rights of God, the Prophet, women, men, the religious and the non-religious are assured because Tunisia is for everyone."

Ennahda, banned under Ben Ali's regime and registered as a political party in March, had pre-empted its victory by announcing on Wednesday it had started coalition negotiations and intended to form a new government within a month.

The new assembly will decide on the country's system of government and how to guarantee basic liberties, including women's rights, which many in Tunisia fear Ennahda would seek to diminish despite its assurances to the contrary.

Analysts say that Ennahda, even in a majority alliance, would be unable to "dictate" its programme to the assembly, having no choice but to appease its alliance partners, a moderate-minded society and the international community on whose investment and tourism the country heavily relies.

Leftist parties may yet seek to form a majority bloc against Ennahda.

The party said earlier Thursday it had met bankers and stock brokers to "reassure them" of its intentions.

PM's remarks

Beji Caid Sebsi, the current prime minister, said that he had no reason to doubt Ennahda's commitment to the secular state and democracy.

In depth coverage of first Arab Spring vote

"I can't judge intentions, that's up to God," Sebsi told Egypt's al-Ahram daily.

"I can only judge by what's public and so far it's positive. At the end of the day, no one can come and change things completely,

"I think [Ennahda] will rule intelligently and deal with reality. It is not necessarily a dark force. Tunisia will continue to move forward and not go against history."

Sebsi, a secularist technocrat who served in Ben Ali cabinets, has occupied the post of caretaker prime minister
since March.

Defying predictions that the election would lead to violence and clashes between police and a hardline Salafi minority,
Sunday's poll was peaceful and was applauded by Western monitors.